povray will run from the command line with no graphics, and obviously will accept a subset of pvoray syntax. What problems are you having with it? It would seem to be more sensible to fix those problems than trying to avoid them.

Good luck finding anything substantial that reads POV-Ray Scene Description Language. There's nothing but POV-Ray and maybe some handy little utilities and maybe some translators out there that can do that, as far as I've seen. (But I'm often missing out on something...)

I didn't check if all these can be run from a command line or from within a program, but I think so.

While POV-Ray's SDL hasn't caught on outside its original turf, Renderman is much more widely accepted. Since that may be outside your interest, I'll say no more.

Another thing - pure raytracing seems to have faded away, mostly. Many renderers combine different algorithms for their total effect. POV-Ray, even, has photon mapping where light is thrown forward from source to surface, as in physical reality. Just how to handle interacting lighting between surfaces (global illumination), and rays passing through transparent/translucent materials that don't originate from the camera, is an active area of research, with the current state of the art being multiple choices depending on the type of scene to render. Thanks to super-duper hardware, compilers and operating systems today, creators of 3D scenes have choices among algorithms, including some previously thought hopelessly inefficient. We live in marvelous times!

So, instead of asking for just an alternative to POV-Ray, explain what kinds of scenes you want to make, with what final visual effects. Would you like HDRI output? Programming in Python for precise complex geometry? There's almost certainly a tool for the job.